In order to treat diseases in an advantageous and successful manner, a reliable diagnosis is often essential. This is the case in particular for diseases which are not only treated in a purely symptomatic manner but in which a cause-specific treatment or healing is sought. A distinction between diseases simply on the basis of the symptoms thereof is often impossible because different diseases result in similar, partially overlapping symptoms although they can be attributed to different medical causes. Thus, changes of the tissue which are triggered by different organic malfunctions can lead to similar or even identical symptoms. For a successful, in particular cause-specific, treatment, account must be taken of these differences.
In order to comply with these medical requirements, the diagnosis works with biopsies, chemical/biological analyses or endoscopic examinations, by means of which the malfunction forming the basis of a disease is intended to be identified. In this case, biopsies are conventionally processed to form fine sections and the tissues or cells are dyed by suitable chemicals. However, the meaningfulness of fine sections dyed in this manner is substantially dependent on the interaction of the tissue with the dyes so that clear and reliable statements are often made more difficult by imperfect dyeing. Furthermore, this procedure is connected with a relatively large number of operating steps and is therefore relatively time-consuming. It can thereby also be used for operation-accompanying analysis only in a limited manner.
For these reasons, in recent years dye-free methods for examining tissues and cells have been developed. In this instance, there have become particularly established Fourier Transform Infrared (FTIR) analyses, in which biological samples are analysed on the basis of the natural IR transmission or reflection spectrum thereof. In this case, complete IR spectrums of the sample are recorded, either by means of point for point mapping (FTIR mapping) or by means of a parallel recording of a plurality of FTIR spectrums by means of an infrared detector with a focal plane arrangement (Focal Plane Array, FPA) (FTIR imaging). However, the conventional FTIR mapping is extremely time-consuming as a result of the point for point mapping. Although the method can be accelerated as a result of the parallel recording of a plurality of spectrums, the sensors (FPA) necessary for this purpose are extremely expensive.
Therefore, the use of one or more quantum cascade laser(s) (QCL) has been discussed in more recent times as an alternative to the established FTIR methods. This involves narrow-band infrared (IR) radiators which have a high spectral energy density and which generally radiate IR radiation of a defined narrow wavelength range. However, more modern devices can also be tuned by means of several hundred wavelengths and thus have a wider IR spectrum. However, reliable results could also previously be achieved with these devices only by using cost-intensive semiconductor detectors (for example, mercury/cadmium/tellurite (MCT) FPA) so that a substantial advantage over conventional FTIR technology has not been afforded in this regard.
Therefore, there is a need for cost-effective and rapid IR analysis devices and methods, in particular for examining biological samples.